This invention relates to a printer. More particularly, the invention relates to a method of characterising a printhead assembly for a printer and to a printhead assembly.
Pagewidth printheads have the advantage of being able to print rapidly but are constituted by a very large number of nozzles. Should any of these nozzles be defective, an inadequate print quality may result.
According to a first aspect of the invention, there is provided a method of characterising a printhead assembly for a printer, the method including
matching a pair of printheads, each printhead including a plurality of inkjet nozzles constructed using microelectromechanical techniques, such that no paired nozzles on the pair of printheads are both defective;
determining which nozzle of a pair is to be used and generating data relating to the nozzle to be used; and
encoding said data and associating said encoded data with the printhead assembly.
The printheads may be pagewidth printheads. In this specification, unless the context clearly indicates otherwise, the term xe2x80x9cpagewidth printheadxe2x80x9d is to be understood as a printhead having a printing zone that prints one line at a time on a page, the line being parallel either to a longer edge or a shorter edge of the page. The line is printed as a whole as the page moves past the printhead and the printhead is stationary, ie it does not raster or traverse the page.
The method may include forming a defect list, which may be in the form of a characterisation vector, of the generated data and storing the vector in a manufacturing database.
Further, the method may include indexing the characterisation vector with an identification device of the assembly. More particularly, the characterisation vector associated with a particular printhead may be stored in the manufacturing database and indexed by a serial number of the printhead.
Further, the method may include encoding the vector in a readable format and applying it to a cartridge of the assembly. Preferably, the characterisation vector is recorded as a barcode on the cartridge.
Then, when the cartridge is installed in the printer, the method may include retrieving the vector from the barcode and writing the vector to a memory means of a printer controller of the printer. The memory means may be a flash memory of the printer controller.
If the cartridge is replaced in the field, a new characterisation vector may be downloaded remotely from the manufacturing database to the printer controller via a network interface of the printer controller using the barcode of the new cartridge.
According to a second aspect of the invention, there is provided a printhead assembly which includes
a pair of matched printheads, each printhead including a plurality of inkjet nozzles constructed using microelectromechanical techniques, the printheads being matched so that no paired nozzles of the pair of printheads are both defective; and
encoded data relating to a defect list associated with the printheads, the defect list providing data relating to which nozzle of each pair of matched nozzles of the pair of printheads is to be used.
The defect list, which may be in the form of a characterisation vector, may be associated with an identification device of the assembly and may be stored in a manufacturing database.
The printhead assembly may include a printhead cartridge, the characterisation vector, in its encoded format, being applied to the cartridge to be readable by a printer when the cartridge is installed in the printer.